linux-kernel - Re: [PATCH v2 1/4] dt-bindings: mfd: Add TI TPS6594 PMIC

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Date:   Tue, 21 Mar 2023 10:03:41 +0100
From:   Julien Panis <jpanis@...libre.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Rob Herring <robh@...nel.org>
Cc:     lee@...nel.org, krzysztof.kozlowski+dt@...aro.org, corbet@....net,
        arnd@...db.de, gregkh@...uxfoundation.org,
        derek.kiernan@...inx.com, dragan.cvetic@...inx.com,
        eric.auger@...hat.com, jgg@...pe.ca, razor@...ckwall.org,
        stephen@...workplumber.org, davem@...emloft.net,
        christian.koenig@....com, contact@...rsion.fr,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, sterzik@...com, u-kumar1@...com,
        eblanc@...libre.com, jneanne@...libre.com
Subject: Re: [PATCH v2 1/4] dt-bindings: mfd: Add TI TPS6594 PMIC



On 3/21/23 08:36, Krzysztof Kozlowski wrote:
> On 20/03/2023 17:35, Julien Panis wrote:
>>
>> On 3/20/23 16:53, Rob Herring wrote:
>>> On Wed, Mar 15, 2023 at 12:07:33PM +0100, Julien Panis wrote:
>>>> TPS6594 is a Power Management IC which provides regulators and others
>>>> features like GPIOs, RTC, watchdog, ESMs (Error Signal Monitor), and
>>>> PFSM (Pre-configurable Finite State Machine) managing the state of the
>>>> device.
>>>> TPS6594 is the super-set device while TPS6593 and LP8764X are derivatives.
>>> As mentioned, the binding needs to be complete. It's missing GPIO at
>>> least. RTC and watchdog may or may not need binding changes.
>> Thank you for your feedback.
>>
>> About GPIO, do you speak about 'gpio-controller'
>> and/or '#gpio-cells' properties ?
> Yes.
>
>> For RTC (and for watchdog, once the driver will be
>> implemented), our driver do not require any node
>> to work. What could make an explicit instantiation
>> necessary in DT ?
> Properties from RTC schema, e.g. start-year, wakeup etc.

TPS6594 RTC driver is being reviewed (this is another patch
series, not merged yet). These properties are not used by our
driver, that's why we did not have to add some RTC node in
the DT (until now, using such properties in our driver was not
requested by RTC sub-system maintainers).

>>>> +  ti,spmi-controller:
>>>> +    type: boolean
>>>> +    description: |
>>>> +      Identify the primary PMIC on SPMI bus.
>>> Perhaps the property name should include 'primary' and 'pmic'.
>>> Otherwise, it looks like it is just marked as 'a SPMI controller'.
>> Including 'primary' and 'pmic' will be more understandable indeed.
>> I will change that in v3.
>>
>>>
>>>> +      A multi-PMIC synchronization scheme is implemented in the PMIC device
>>>> +      to synchronize the power state changes with other PMIC devices. This is
>>>> +      accomplished through a SPMI bus: the primary PMIC is the controller
>>>> +      device on the SPMI bus, and the secondary PMICs are the target devices
>>>> +      on the SPMI bus.
>>> Is this a TI specific feature?
>> I don't think so. I will double-check that.
>> If not, shall I remove the 'ti,' prefix ?
> Somehow reminds me qcom,bus-id, but the wording and code are not exactly
> the same. The question here is whether this is generic feature of all
> SPMI devices or PMICs, or device specific. If it is generic, then naming
> and type should be chosen a bit more carefully and then indeed skip
> "ti," prefix.

Apparently, it's not TI specific. Besides, all the information
I found about SPMI were related to PMIC devices. I have to
double-check with TI, though.
I will either rename it to 'ti,primary-pmic' if TI specific or
'primary-pmic' if not TI specific.

>
>>>> +
>>>> +  system-power-controller: true
>>>> +
>>>> +  interrupts:
>>>> +    maxItems: 1
>>>> +
>>>> +  ti,multi-phase-id:
>>>> +    description: |
>>>> +      Describes buck multi-phase configuration, if any. For instance, XY id means
>>>> +      that outputs of buck converters X and Y are combined in multi-phase mode.
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    enum: [12, 34, 123, 1234]
>>> coupled regulator stuff doesn't work here?
>> Coupled regulator stuff works here.
>> Is it also necessary to specify some 'allOf' logic here to ensure
>> that mutual exclusions described below (for regulators) will be
>> applied ?
> None of other regulators do it but you could add something.
>
>
> Best regards,
> Krzysztof
>